DTC P0101: MAF System Performance: Description

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Mass Airflow (MAF) sensor measures speed and density of air entering intake manifold. ECM converts this input to a mass of air per unit time to correctly fuel engine. MAF output voltage is a function of power required to keep sensing element at fixed temperature greater than outside air temperature as incoming air cools sensing elements. Output voltage varies between 0.20 and 4.8 volts under all normal engine running conditions. As a validity check, ECM calculates airflow based on engine speed, throttle valve position from TP sensor, intake air temperature, and engine coolant temperature, then compares this to actual reading from MAF sensor. DTC sets when ECM determines calculated airflow value and actual airflow value are not within a calibrated range.